Graphite powders, both natural and synthetic, are naturally hydrophilic and are easily dispersed in water without the use of emulsifying or wetting agents. As a result these powders do not adhere well to hydrophobic surfaces especially when applied to such surfaces under wet conditions such as from an aqueous suspension.
Graphite has been extensively studied for many years and has been treated in numerous manners in attempts to alter or improve its physical, chemical and electrical properties to adapt it to specific end uses, and also as a matter of scientific investigation.
In applicant's studies of both natural and synthetic graphite powder, he has observed that the graphite particles or flakes have a dual characteristic. Each particle behaves as if part of its surface is hydrophobic and part of its surface is hydrophilic and it is the net effect of these individual particles when combined into a powder that results in the observed hydrophilic property of conventional graphite powders.
A cursory search of the vast amount of literature on graphite indicates that the net hydrophilic effect of the graphite can be rendered entirely hydrophobic, for example, by grinding the graphite under n-heptane for eight hours. Such a treatment is reported to render the graphite powder oleophilic, Proc. Roy. Soc. Lond. A. 314, 473-498 (476), (1970) A. J. Groszek.
Graphite has also been treated with many other polar and non-polar solvents of materials. Such additional treatments have been reported in THE JOURNAL OF PHYSICAL CHEMISTRY 71 No. 11, 3408-3413 (1967) Pierce and Ewing as well as in the A. J. Groszek publication above. The Pierce and Ewing publication does not, however, report any findings relating to the hydrophilic or hydrophobic properties of graphite.
There are probably other publications dealing with the treatment of graphite with both polar and non-polar materials and some may also report findings relating to the hydrophilic or hydrophobic properties of graphite, but the applicant is not aware of any such publications other than those reported herein. As noted above, applicant's search was cursory since the vast amount of literature on graphite rendered a detailed search economically prohibitive.